Interleukin-9 ("IL-9" hereafter) is a pleiotropic cytokine, produced primarily by T helper cells. It was originally described as a growth factor for T cells, and then for mucosal type mast cells. Additional properties have been ascribed to this cytokine, including, but not being limited to, erythroid differentiation, Ig production, neuronal differentiation, granzyme expression, and induction of expression of high affinity IgE receptors in T helper clones. Review articles discussing these and other properties are Renauld, et al, Adv. Immunol. 54: 79 (1993); and Demoulin, et al, Int. Rev. Immunol. 16:345 (1998), both of which are incorporated by reference. The molecule was first observed in murine form, and was referred to as P40. The molecule was isolated and cloned, as was its receptor, in both murine and human form. See, e.g., U.S. Pat. Nos. 5,208,218; 5,157,112; 5,580,753; 5,587,302; 5,734,037; 5,750,377; 5,116,951; 5,180,678; and 5,789,237, all of which are incorporated by reference. IL-9 has been implicated in inhibiting production of IgE and enhancing production of IgG (U.S. Pat. Nos. 5,132,109 and 5,246,701); in modulating cell apoptosis (U.S. Pat. No. 5,824,551), treatment of autoimmune disorders (U.S. Pat. No. 5,830,454), and in treatment of interstitial lung disease (U.S. Pat. No. 5,935,929). All of these patents are incorporated by reference.
In view of its restricted production by Th2 clones in vitro (Gessner, et al, Immunobiology 189:419 (1993) as well as its expression in Th2 type responses in vivo (Grencis, et al, Immunology 74:329 (1991); Svetic, et al, J. Immunol. 150:3434 (1993); Faulkner, et al, Infect. Immunol. 66:3832 (1998)), IL-9 is considered to be a Th2 cytokine that is inducible by both IL-4 dependent and IL-4 independent pathways. See Gessner, et al, supra; Kopf, et al, Nature 362:245 (1993); Monteyne, et al, J. Immunol. 159:2616 (1997). Others have described dependence of IL-10 on IL-9 (Grencis, et al, supra; Houssiau, et al, J. Immunol. 154:2624 (1995)). Further, IL-9 has been implicated in response to parasitic infections (Grencis, et al, supra; Svetic, et al, supra; Faulkner, et al, supra; Else, et al, Immunology 75:232 (1993)); allergies (Petit-Frere, et al, Immunology 79:146 (1993)); and inflammatory processes (Louahed, et al, J. Immunol. 154:5061 (1995)); however, the role of interleukin-9 in antibacterial host defense has not been investigated.
Septic shock is a condition resulting from uncontrolled, sequential release of mediators having proinflammatory activity following infection with Gram negative bacteria, and in response to endotoxins. See, e.g., Tracey, et al, Science 234:470 (1986); Alexander, et al, J. Exp. Med. 173:1029 (1991); Doherty, et al, J. Immunol. 149:1666 (1992); Wysocka, et al, Eur. J. Immunol. 25:672 (1995). Endotoxin exerts its effect by inducing potent, macrophage activation, and release of cytokines such as TNF-.alpha., IL-1, IL-6, IL-12, and IFN-.gamma.. See VanDeuren, et al, J. Pathol. 168:349 (1992). In particular, IL-12, in concert with TNF-.alpha., or B7 costimulation, can act as a potent inducer of IFN-.gamma. production by T and NK cells. See D'Andrea, et al., J. Exp. Med. 178:1041 (1993); Murphy, et al, J. Exp. Med. 180:223 (1994); Kubin, et al, J. Exp. Med. 180:211 (1994). The central role of proinflammatory cytokines in the pathogenesis of endotoxic shock is underlined by the occurrence of high levels of circulating cytolines in both humans and experimental animals during endotoxemia. See Stevens, et al, Curr. Opin. Infect. Dis. 6:374 (1993).
The triggering of regulatory mechanisms during sepsis can oppose macrophage activation. (Heumann, et al, Curr. Opin. Infect. Dis. 11:279 (1998)). This, in turn, can alleviate an overwhelming, dysregulated inflammatory response, which leads to pathological effects, and potential death by the host. A substantial body of literature shows that anti-cytokine action can improve the outcome of subjects challenged by LPS or Grain negative bacteria. Beutler, et al, Science 229:689 (1985), and Heinzel, et al, J. Immunol. 145:2920 (1990), teach administration of neutralizing anti-cytokine antibodies, while Ohlsson, et al, Nature 348:550 (1990), teach administration of IL-1R antagonists, Bozza, et al, J. Exp. Med. 189:341 (1999) teach targeting of genes encoding proinflammatory cytokines, and both Pfeffer, et al, Cell 73:457 (1993), and Car, et al, J. Exp. Med. 179:1437 (1994), teach that administration of cytokine receptors can diminish lethality in experimental endotoxemia.
Both interleukin-10 ("IL-10"), and interleukin-4 ("L-4") have been shown to be efficacious in treatment of septic shock and LPS induced pathology. With respect to IL-10, see Marchant, et al, Eur. J. Immunol. 24:1167 (1994); Howard, et al, J. Exp. Med. 177:1205 (1993); Gerard, et al, J. Exp. Med. 177:547 (1993). With respect to IL-4, see Baumhofer, et al, Eur. J. Immunol. 28:610 (1998), Jain-Vora, et al, Infect. Immun. 66:4229 (1998), and Giampetri, et al Cytokine 12(4): 417-421 (2000).
The known efficacy of IL-4 and IL-10, however, does not permit the skilled artisan to predict efficacy of IL-9 in treating and preventing septic shock and/or endotoxemia. The known properties of IL-9 are not such that one could attribute efficacy against Gram negative bacteria.
It has now been found that IL-9 actually induces IL-10, leading to efficacy in preventing septic shock and endotoxemia. This is contrary to expectation, since it has in fact been argued that IL-10, in conjunction with IL-4, stimulates IL-9 production by human PBLs, and that IL-9 production is, in fact, inhibited by antibodies to IL-10. See Houssiau, et al, J. Immunol. 154:2624 (1995). Hence, it is quite surprising and unexpected that IL-9 induces IL-10, and can be used in methods to prevent and/or to treat conditions where an increase in IL-10 levels is desirable. These, inter alia are features of the invention, as elaborated in the examples and disclosure which follow.